Magnesium base alloy



Patented Nov. 12, 1940 1 UNITED STATES PATENT OFFICE- land, Company, Michigan Mich, assignors to Midland, Mich., a corporation I The Dow Chemical No Drawing Application November 13, 1939,

. Serial No. 304,127

3Claims.

in various structural and mechanical arts where a light weight metal is highly desirable, such as for use in making large castings, iorgings, and the 10 like. However; the use of these alloys in rolled form to make sheet metal articles requiring forming operations, such as bending, drawing, or the like, has not progressed as rapidly due to the fact that in general alloys of good i'ormability, permit- (cits-10s have found that in general the preferred combination of. properties, suchas the most desirable ductility for forming operations associated with high tensile and yield strengths is found in alloys containing from 3 to 5 per cent vof thal- 5 lium and from 0.1 to 0.3 per cent of calcium.

I'he following table, which lists some of the properties of sheet metal made from our new alloy and compares these properties with those of the related binary alloys, illustrates the improve ment in yield strength, tensile strength, and ductility or formability, as represented by per cent increase in elongation, of the new alloy over the corresponding properties of the closely related per cent of thallium and from 0.05 to 1 per centv 50 of calcium, the balance being substantially all magnesium, is endowed with the afore-mentioned properties. While the properties of improved formability or ductility associated with high tensile and yield strengths are manifest over the entire range of composition above indicated, we

ting relatively sharp bends to be made without alloys. 15

Table N ommmpg'wn m manta c010 rolled (magnesium-remainder) ensil Percent Yield Tensile Percent 08 T1 Yield atren gth in elongation in strength in strength in elongation in 26 lballq. in. IDSJIQ- in. 2 01100 lbsJoq. in. lbs./sq. in 2 inches 26 03 17,000 000 13 21,000 32,000 2 0.0 10,000 221000 a 22. 20,000 2 0.2 0.3 000 02,000 14 21,000 02,000 1 1.0 10,000 ram 3 20,000 01,000 2 0.2 1.0 10,000 02,000 10 23,000 34,000 2 The properties listed in the above table under the section headed by the term annealed were obtained by first rolling the alloys at a temperature between about 600 to 700 F., and thereafter annealing them at various temperatures through a temperature range of from 400 to 800 F. The properties selected for the table were those of the annealedspecimens which exhibited the maximum elongation. The properties listed under the section headed cold rolled" were obtained by subjecting specimens of the alloys which had been hot rolled at a temperature of from 600 to 700 F. to additional rolling in the cold state, to bring about a total reduction in thickness of from 2 to 10 per cent. The prop- 50 erties selected for the table were those of the cold rolled specimens which showed the greatest tensile and yield strengths, while having at least a 1 per cent elongation in 2 inches.

By comparison of the'properties set forth in 00 the above table it will be observed that in ahnost every instance every property of the new ternary alloy is superior to those of the parent binary alloys having similar percentages of the alloying ingredient present. Further, it will be observed that the combined properties of the new alloy are always superior to those of the parent alloys.

While the new alloy is most useful in wrought form, such as sheets, due to its formability char-' acteristics it may also be suitably used in making castings, forgings, extruded forms, and the like.

The new alloy may be compounded in any of the ways known to the art, such as by adding the alloying constituents to the molten magnesium under a suitable flux. The flux should be substantially free of magnesium chloride if the calcium content is to be above 0.3 per cent. In those instances where an alloy is to be compounded containing less than 0.3 per cent of calcium, magnesium chloride may be present in the flux without exerting a deleterious effect. In the latter case, however, it is usually preferable to add the calcium last without too much stirring or agitation in order that the loss of calcium into the flux will be substantially prevented.

We claim:

1. A magnesium base-alloy containing from 0.1 to 10 per cent of thallium and from 0.05 to 1.0 per cent of calcium, the balance being magnesium.

2. A magnesium base alloy containing from 3 to 5 per cent of thallium and from 0.1 to 0.3 per cent of calcium, the balance being magnesium.

3. A magnesium base alloy consisting of approximately 4 per cent of thallium and 0.2 per cent of calcium, the balance being magnesium.

JOHN C. MCDONALD. JOSEPH D. HANAWALT. 

